Method for producing foamed slag on high-chromium melts in an electric furnace

Abstract

The invention relates to a method for producing foamed slag on high-chromium steel melts in an electric furnace, whereby a mixture consisting of a metal oxide and carbon is introduced into the furnace, the metal oxide in the slag is reduced by the carbon, and the gases created in the slag form bubbles which thus foam up the slag. In order to be able to control the gas formation and thus the foaming process, the mixture consisting of a metal oxide and carbon and optionally an iron carrier is introduced as preforms, such as pellets, which are compressed and/or provided with a binding agent. The gas formation can be controlled in terms of location, type and time, by adjusting the characteristics of the pellets, especially the density and/or compression characteristics thereof.

1 . Method for producing foamed slag ( 7 ) on high-chromium steel melts ( 6 ) in an electric arc furnace ( 1 ), wherein a mixture of a metal oxide and carbon is introduced into the furnace ( 1 ), the metal oxide is reduced by the carbon in the slag ( 7 ), and the resulting gases form bubbles in the slag, which thus cause the slag to foam, wherein the mixture of metal oxide and carbon is introduced into the furnace as compressed preforms ( 8 ) and/or preforms ( 8 ) provided with a binder. 
     
     
         2 . Method in accordance with  claim 1 , wherein the density of the preforms ( 8 ) is adjusted in such a way that they float in the slag ( 7 ). 
     
     
         3 . Method in accordance with  claim 1 , wherein the density of the preforms ( 8 ) is adjusted in such a way that they float in the slag near the phase boundary between the melt ( 6 ) and the slag ( 7 ). 
     
     
         4 . Method in accordance with  claim 2 , wherein the density of the preforms ( 8 ) is adjusted by the addition of an iron carrier. 
     
     
         5 . Method in accordance with  claim 1 , wherein the density of the preforms ( 8 ) is adjusted in such a way that they disintegrate in the slag ( 7 ) uniformly and slowly, and the evolution of gas occurs uniformly and over a relatively long period of time. 
     
     
         6 . Method in accordance with  claim 1 , wherein the density of the preforms ( 8 ) is adjusted in such a way that they disintegrate with a time delay. 
     
     
         7 . Method in accordance with  claim 1 , wherein a flux, preferably limestone, is additionally added to the mixture. 
     
     
         8 . Method in accordance with  claim 1 , wherein a slag thinner, preferably CaF 2 , is additionally added to the mixture. 
     
     
         9 . Method in accordance with  claim 1 , wherein a reducing agent, preferably silicon and/or aluminum, is additionally added to the mixture. 
     
     
         10 . Method in accordance with  claim 1 , wherein the preforms ( 8 ) are introduced through the sidewalls ( 10 ) and/or the furnace roof ( 4 ) of the electric arc furnace ( 1 ). 
     
     
         11 . Method in accordance with  claim 1 , wherein the preforms ( 8 ) are introduced into the slag ( 7 ) in a directed way in the vicinity of or directly at the hot spots of the electrodes ( 5   a - c ).